Immunohistochemistry of embryonic chick collagens will be conducted with ferritin and fluorescein labeled antibodies. The relation of collagen to the cell surface will be studied with these techniques in the developing chick cornea. The role of extracellular matrix (ECM) in cell migration and the changes in ECM that take place during muscle to cartilage transformation will be investigated in vitro. Radioactive isotopes will be used to analyze ECM production. BIBLIOGRAPHIC REFERENCES: Linsenmayer, T.F., Smith, G.N., and Hay, E.D.: In vitro synthesis of two collagen types by embryonic chick corneal epithelium. Proc. Nat. Acad. Sci. USA 74: 39-43, 1977. Hay, E.D.: Cell-matrix interaction in embryonic induction. In: International Cell Biology 1976-1977 (B.R. Brinkley and Keith R. Porter, eds.) The Rockefeller Press, New York, in press.